US 2005/0174780 A1 discloses a lighting device comprising light emitting diodes (LEDs) as a light source. The lighting device comprises a socket, which can be electrically connected to a receptacle, and a cooling fan for forcibly circulating air. The cooling fan is received in a main body, which has a plurality of radial partition walls formed in the outer peripheral surface thereof in such a manner as to be spaced apart with a gap between them having a slit shape for ventilation. The LEDs of the lighting device are cooled by the air which is circulated by the cooling fan.
This cooling by circulated air has the drawback that dust and other contaminations from outside the lighting device are transferred to the cooling fan, the LEDs and other elements of the lighting device, such as control electronics for controlling the LEDs and the cooling fan. This contamination reduces the cooling performance over time and the lifetime of the lighting device.